Alkoxy-substituted aliphatic carboxylic acid compounds



Patented May 29, 1945 UNMED STA'EES RATENT- ALKOXY-SUBSTITUTED ALIPHATIC CAR- BOXYLIC ACID COMPOUNDS Lucas P. KyridesyWebster' Groves, Ma, assignor to Monsanto Chemical Company, St. Louis, Mo., a. corporation of Delaware No Drawing. Application March 2, 1942, Serial No. 432,998

2 Claims.

The present application is a continuation inpart of my prior copending application, Serial Number 181,597, filed December 24, 1937, which has issued as Patent Number 2,283,214. The invention, as it pertains specifically to the present application, is based upon my discovery that alkoxy-substituted acids and alkali-metal salts of such acids obtained by the addition or condensation of aliphatic alcohols containing from five to sixteen carbon atoms, inclusive, in the molecule, such as dodecyl (lauryl) alcohol, with various unsaturated aliphatic carboxyllc acids possessing the alpha-beta-enal grouping, are characterized by pronounced surface activity. These compounds are comparable in their surface activity to similar well-known washing,'wetting and emulsifying agents such as the sulfated alcohols and the sulfonated alkyl aromatic hydrocarbons commonly used for this purpose, but many of them do not foam or lather as readily when added to water in the manner that is typical of other wetting agents. This failure to foam is a definite advantage for certain purposes, and does not detract from their desirability as wetting agents or detergents.

The alkoxy-substituted aliphatic carboxylic acids to which the present invention pertains are those derived from aliphatic alcohol containing from five to sixteen carbon atoms, inclusive, in the molecule. Such alcohols are the various am'yi, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl (lauryl), tridecyl, tetradecyl, pentadecyl and hexadecyl (palmityl) alcohols, many of which are obtained by hydrogenation of the corresponding fatty acids or fatty acid esters and are available in commercial quantities.

Theforegoing alcohols are condensed with unsaturated aliphatic carboxylic acids containing the alpha-beta-enal grouping, preferably in the form of esters. Unsaturated aliphatic carboxylic acids of this type are fumaric or maleic acid, HOOCCH=CHCOOH, itaconic acid,

citraconic acid, CH3C(COOH) =CHCOOH. acrylic acid, CH2=CHCOOH, and crotonic acid, CH3CH=CH-COOH. These acids possess the following structural formula:

in which R is selected from the group consisting of hydrogen, alkyl and carboxyl radicals. Maleic acid is the most common and most readily available acid of this series and hence compounds derived from that acid are particularly considered throughout this specification. Aromatic acids, such as phthalic acid, in which the reactiveportion of the alpha-beta-enal grouping is partly incorporated in the phenyl nucleus, are not operative.

The general formula of the alkoxy-substituted acids which are specified in the present application may be represented as:

in which R. is a hydrogen, alkyl or carboxyl radical and alkyl is an alkyl group having not less than five nor more than sixteen carbon atoms. However it is not definitely ascertained to which of the two pivotal carbon atoms in the above formula the alkoxy (alkyl0) group and the hydrogen atom from the alcohol are attached, or whether a mixture of both possible types of compounds is formed, hence the brackets are used to indicate this uncertainty. Stated more generally, the compounds specified in the present application are those derived from the condensation of an alcohol as above specified with an unsaturated carboxylic acid as above specified, and include both the alkoxy-substituted acids thus formed and the water-soluble, particularly alkalimetal, salts of such acids.

In effecting the addition or condensation, an ester or other suitable compound, in which the carboxyl groups of the unsaturated acid are blocked, is preferably used. The condensation product is then hydrolyzed to yield the desired alkoxy-substituted acid or saponified to yield a salt of the acid. When maleic acid or a suitable ester or other derivative of maleic acid is used in the condensation, the resulting compound is an alkoxy-succinic acid derivative; acrylic'acid yields alcohol or metal alcoholate and an ester of the.

unsaturated acid containing the alpha-beta-enal grouping. When an alcoholis used the condensation may be effected in the presence of sodium;

Alternatively, I may convert the alcohol to a metal alcoholate by adding sodium hydroxide to the alcohol and removing the waterof reaction, and thereafter use the sodium alcoholate, as more gggcifically described in Towne Patent No. 2,120,-

Insteadof using the ester of the unsaturated acid, for example, 'dieth'yl maleate, a salt of. the half-ester, such as monoethyl maleate, or a salt of the acid, such as disodium maleate, may be used. The resulting ester, half-ester salt, ,or salt of the alkoxy-substituted acid is thereafter converted to the acid, by acid hydrolysis, or to a salt by saponification. In preparing lauroxy-succinic acid, as described in Example 1 which follows,

lauryl alcohol and diethyl maleate are condensed in the presence of metallic sodium under anhydrous conditions. The resulting diethyl ester of lauroxy-succinic acid is saponified'and the salt formed after saponiilcation is used as such or is converted to the acid.

Instead of starting with diethyl maleate I may start with the half .ester, monoethyl maleate, by

forming the sodium salt of the half ester. and reacting this salt with lauryl alcohol under anhydrous conditions with metallic sodium. SapOniflcation of the resulting salt and recovery as before, yield lauroxy-succinic acid.

To prevent trans-esterification I prefer to use an ester of the unsaturated acid containing the Example 1.--Lauro:cv-succinic acid Three hundred forty-four (344) grams of diethyl maleate (approximately 2 mols) and 410 grams of lauryl alcohol (approximately 2.2 mols) were placed in a flask provided with a reflux condenser. Approximately 5 grams (0.2 gram atoms) of sodium metal (in small pieces or in rolled form) were then continuously added. Reaction started immediately and the mixture became warm. The mixture was allowed to stand until the initial reaction subsided and it was thereupon heated on a steam bath for several hours. To the mixture was then added alcoholic sodium hydroxide in quantity'su-ilicient to saponify the ester and the mixture was subjected to refluxing. After saponiflcation was complete the mixture was cooled, ethyl alcohol was distilled from the mixture and unreacted lauryl alcohol was extracted from the alkaline solution with a non-aqueou solvent. The reaction. mixture was then made acid with hydrochloric acid and the precipitated lauroxy-succinic acid was removed by extraction with chloroform. The residual solution contained maleic acid resulting from unreacted diethyl maleate. The lauroxy-succinic acid was converted to its sodium salt and recovered as such.

The free lauroxy-succinic acid is a solid of waxy appearance and its sodium salt is a mass resembling soapin appearance and feel.

Example 2.Decoa:u-succinic acid this solution was then added to.396 grams (approximately 1 mol) of di-n-decyl' maleate. The reaction mixture was allowed to stand in a stoppered flask for about 100 hours, after which the mixture was hydrolyzed by shaking with about 590 cc. of water. About 400 cc. of dioxane was then'added tothe mixture and it was saponiiled with about 100 grams (approximately 2.5 mols) of sodium hydroxide by refluxing therewith for about 17 hours. The mixture was cooled and the resulting layers were separated. The aqueous layer was washed about 4 or 5 times with benzene to remove any decyl alcohol and dioxane remaining in the aqueous solution. The aqueous solution was acidified with hydrochloric acid and the resulting oil was washed with saturated salt solution.

The oil, consisting predominantly of decoxysuccinic acid, was dissolved in methanol and cohverted to the calcium salt by adding a slight excess of an aqueous solution of calcium chloride.

A heavy precipitate of the calcium salt of decoxysuccinic acid separated. The precipitate was illtered with the aid of suction and washed with a small amount of methanol. The salt was then added to an excess of 75% to aqueous sulfuric acid mixed with an equal volume of benzene, and the calcium sulfate that separated was removed by filtration. The calcium sulfate precipitate was added to another portion of 75% to 85% sulfuric acid mixed with an equal volume of benzene to remove any decoxy-succinic acid adhering thereto. The solutions. were then combined and the benzene and sulfuric acid layers were separated. The sulfuric acid layer was further extracted with benzene and the benzene extracts were combined and filtered. The filtered benzene extracts were then evaporated and the acid solidified on cooling. at The neutralization number of the decoxy-suc- 'cinic acid obtained in this manner was 151. The molecular weight of decoxy-succinic acid is 274, hence the theoretical neutralization number is 137. The acid can be converted to the sodium salt by adding droxide thereto.

Standard soil launderometer tests sion of carbon black, vegetable oils and mineral sodium carbonate or hyoilein weter. The fabric is then aged for a predetermined period. The 881118 of the fabric is important because the soil is more clificult to remove as it becomes older. The soiled seem is then washed in o leunderometer end each sample is tested in triplicate at various wash lnwvols (ill, 20, 36) end eo minutes). The washed mule is then dried and the lightening or the fabric E determined, using e. Pulfrlch photometer. The relative detereency is then established.

The table illustrates the improvement in whiteness expressed es "per cent beryte white um obtained with the detergents when water.

Sodium salt oi 11-11% bowl suesucainio mid Mm Belt Santommw cueeinio eoiri mores" Soft water 59 pm.):

1st war-$1 (f2) min.) md wash (20 mm).--" 3rd west 5% mln.3. 4th wash til min.

for. rubber latex, es flotation reagents, as piement-treetlng eeente to improve disoereifoilitl' ueutly desirable for many applications depend ent upon their surface activity.

To the acids and salts of the invention verif one sediments or builders-may be added, for exused in soft 1 eoueous eolution and thus obviates the step or ample, such materials. as sodium carbonate, sodium euliete, magneaum sulfate, etc. eerticuleriv when the products are to be used as detergents. when sodium carbonate is used in this manner the free acid instead of its sodium salt may be incorporated into the composition, since the sodim carbonate converts the acid to the salt in mover-ting the free acid to the salt.

and grinding properties, as rubber-compoundin ingredients end the like. They ere oi especial edepteti for use in alkaline washing oeerelltzoet By the term wetting agent es ueefi ill the eoeeifieetiom end cleime is to lie meereeoee em The sogilum salt of leuroxwmonoethyl sucoinete, which is louroxy-succinic acid in which one hydrogen of the cor-boxy! group has been repieced by sodium and the hydrogen of the other carbonyl group has been replaced by ethyl,

greatly inierior to the diaodlum salt of leurow succlnic acid. The aliesters of leuroxy-euccmic acid are relatively insoluble in woter end are therefore not suitable wetting agents or cie- I 

